Efficacy and Safety of Irinotecan Plus S-1 (IRIS) Therapy to Treat Advanced/Recurrent Colorectal Cancer

BACKGROUND: 5-Fluorouracil (5-FU), leucovorin, and oxaliplatin (FOLFOX) therapy and 5-FU, leucovorin, and irinotecan (FOLFIRI) therapy are standard chemotherapies to treat advanced/recurrent colorectal cancer. However, these chemotherapies require continuous infusion of 5-FU for a prolonged time of 40 h or more, every two weeks. Accordingly, these chemotherapies require hospitalization and placement of a central venous catheter. Because of frequent catheterization, long-term use of these therapies potentially risks complications such as infection and thrombosis. In contrast, S-1 (tegaful, gimeracil, oteracil) combined with irinotecan (IRIS) therapy involves giving one drug orally and infusing the other for about two hours every two weeks, so placement of a central venous catheter is not necessary. The current study examined the efficacy and safety of IRIS therapy in 90 patients at this Hospital who underwent such therapy to treat advanced/recurrent colorectal cancer. PATIENTS AND METHODS: The study comprised 90 patients who underwent IRIS therapy to treat advanced/recurrent colorectal cancer from December 2004 to December 2011. RESULTS: The ratio of male-to-female patients was 64:26. The mean age at the start of IRIS therapy was 64.5 years, and patients underwent an average of 11 courses of therapy. The response rate to IRIS therapy was 14.8%, the disease control rate was 60.5%, and the overall survival time was 26.7 months. The incidence of adverse events was 70.0%, and the incidence of grade 3 or more severe adverse reactions was 17.8%. CONCLUSION: In comparison to the standard therapies of FOLFOX and FOLFIRI, IRIS therapy had a lower response rate but led to an equivalent overall survival time. IRIS therapy had a low incidence of serious adverse events and allowed patients to continue therapy on an out-patient basis. These findings indicate that IRIS therapy may be a useful form of chemotherapy to treat advanced/recurrent colorectal cancer.